1. Field of the Invention
The present invention relates to a toner for developing an electrostatic image in an image forming method such as electrophotography or electrostatic printing, or a toner according to a toner-jet mode.
2. Description of the Related Art
An image forming method involving visualizing an electrical or magnetic latent image on a recording body by using toner is employed for developing the latent image. A representative example of the image forming method is an electrophotographic method. The electrophotographic method involves: electrically forming a latent image on a photosensitive member by using various means; developing the latent image with toner to form a toner image; transferring the toner image onto a transfer material such as paper as required; and fixing the toner image to the transfer material by employing fixing means such as heating, pressurization, pressurization under heat, or solvent steam to provide an image.
A heat roller fixing method or a film fixing method involves causing a heat roller or a fixation film to pass a toner image on a sheet to be fixed while contacting the heat roller or the fixation film with the toner image to perform fixation. In each of the fixing methods, the surface of the heat roller or of the fixation film and toner on the sheet to be fixed contact with each other, so thermal efficiency upon fusion of the toner to the sheet to be fixed is extremely good. Accordingly, the fixing methods each enable fixation to be performed quickly, and each are extremely useful in an electrophotographic device. However, in each of the above fixing methods, the surface of the heat roller or of the fixation film contacts with the toner in a molten state, so part of the toner adheres to the surface of the heat roller or of the fixation film. As a result, an offset phenomenon in which the toner adhering to the surface of the heat roller or of the fixation film transfers to a next sheet to be fixed again occurs, so the sheet to be fixed is contaminated in some cases.
An additional improvement in toner performance such as fixability, offset resistance, or high durability is needed for coping with recent demands on reductions in size and weight, energy savings, and an improvement in reliability.
Japanese Patent Application Laid-Open No. 2003-280270 discloses a toner which: uses a polyester resin as a binder resin component; contains 5 to 30 mass % of THF insoluble matter; and specifies a relationship between an elution volume and light scattering intensity in the GPC-MALLS analysis of THF soluble matter obtained with a light scattering detector.
At present, however, an additional improvement in the low-temperature fixability of toner and gloss of the toner, the widening of the fixable temperature domain of the toner, and an additional improvement in development durability of the toner over a long time period have been required.